While in New Orleans to film scenes for Adam Jones, Bradley Cooper also had an important agenda for his downtime: stopping in for dinner at one of his favorite local eateries, Eleven 79 – with girlfriend Suki Waterhouse in tow.

Bradley Cooper didn't necessarily have the wildest of birthday celebrations, but his special day certainly didn't go unnoticed.

The Silver Linings Playbook star, who flew in on Bombardier's Hollywood Reporter Palm Springs shuttle from Santa Monica, Calif., and turned 38 on Saturday, was greeted by a slew of screaming fans when he arrived on the red carpet at the 24th Annual Palm Springs International Film Festival Awards Gala in Palm Springs, Calif.

"Bradley started interacting with his fans and then they broke out into song, chanting 'Happy birthday to you,'" an onlooker tells PEOPLE.

Running late into the event because of the fan holdup, Cooper whisked by many of the reporters, and when asked about his birthday plans, answered with a smile, "I'm here!"

Bradley Cooper and Robert De Niro were on hand to celebrate their film Silver Linings Playbook at the Weinstein Company's special event at the Chateau Marmont in West Hollywood on Friday.

At the candle-lit dinner party, De Niro enjoyed a Purity Vodka martini, while Cooper posed for photos with Zoe Saldana. De Niro spent part of the night talking with Mel Gibson and Jane Fonda, who were also in attendance.

Seated on a big comfy couch, Cooper relaxed with three other men – who looked like business associates, an onlooker tells PEOPLE.

"Bradley was beaming with happiness," the source says of the Silver Linings Playbook actor. "He was very engaged in conversation, but every now and then would look out the large windows to enjoy the amazing view."

Jones looked "funky and adorable" the source adds. Wearing a high ponytail, black framed glasses, jeans and a sweater, the Parks and Recreation actress was joined by a male friend as she greeted other guests. "She was laughing and joking and really lively throughout the night," the source says.

They made a PDA-filled splash at Sundance, and new couple Bradley Cooper and Zoe Saldana stepped out once again at L.A's SoHo House for a Grey Goose-hosted party the night before the Academy Awards. But this time around, they seemed to be playing things more coy – possibly because the reigning Sexiest Man Alive had brought his mom, Gloria, out!

Cooper had his arm around his mother (who's already met Zoe), and led the way through the Weinstein Company bash as Zoe, Casey Affleck and a pal followed them through the crowd. Meanwhile, Scarlett Johansson and new beau Nate Naylor walked hand-in-hand through the party together. The pair stopped to chat with Russell Simmons before heading out. – Julie Jordan